Lines that are parallel to one another and level with the ground plane, such asfurrowsin a plowed field, appear to meet at the same point on the horizon line. This point is known as the vanishing point. The vanishing point is one of the most important points to establish accurately in order to draw the object accurately. If a vanishing point is misplaced, the object will be distorted in the drawing.
Look at a long table from one end and notice that the far end appears to be smaller than the near end. We know that the ends of the table are the same width, but due to perspective, we notice the viewing difference. This is the illusion of depth as shown by perspective. If we draw imaginary lines along the sides of the table and extend them out towards the horizon, they will meet or the horizon line. If we then put a dot at the point where they meet, we have established a vanishing point. Lines that are parallel to the table side lines will also meet at the same vanishing point on the horizon line. All objects in the picture will also seem to grow smaller as they move into the picture, toward the horizon line. So, the horizon line plays a number of important roles in the rules of perspective. Now that we have a basic understanding of some of the terms used in perspective. Let’s consider the number of perspective, and the ones that are most important to us.
Vanishing Point (VP) is a point where the edges of an object all seem to line up in the distance. A drawing may have only one VP or it may contain several vanishing points depending on the complexity of the subject, which are almost always placed on the horizon line. An off-horizon line vanishing point is used to define planes such as stairs, hills, angles or roofs. Returning to the vanishing point example of a continual line of telephone poles across the flat landscape, let us start with an exercise. From our stationary point of view, the telephone poles seem to get smaller and smaller until they vanish at one point along the horizon line as we discovered earlier. Those poles were randomly placed along the perspective lines.
How do we make the telephone poles look to be at an equal distance from each other?
Start by drawing a horizon line with a vanishing point near half-way. Draw one large stick that rises over and under the horizon line at a 90-degree angle. Use a straight edge to draw a line from the top and bottom of the stick back to the vanishing point. Using these perspective lines as a guide, draw another stick parallel to the first at a distance you think the poles should be apart.